Screw jack



Dec. 15; 1931. F. H. SCHWERIN 1,837,137

SCREW JACK Filed Dgc. 5, 1929 3 Sheets-Sheet 1 fATTORN .1- F.'H.SCHWERIN 1,837,137

SCREW JACK Filed Dec. 5, 1929 3 Sheets-Sheet 2 61 ATTORNEY Patented Dec.15, 1931 UNI-TE o FRANK mscfiwnnlmor BELLEVUE, imimsnvama, asslsn'oa To.in nun-Norman MANUFACTURING comma .01 rrrrsnnmn, PENN rmmsnvmm Vilma, Aconromrrorr or.

's mwmcx The invention relates to self-lowering One of the principalfeatures-whichhas been sought is 11 htness in weight, so'that the jackcan be rea ily carried-about... Another w object is to a secure aconstruetion whlchiis adapted for economicalmanufacture.. I hepurpose,also, is'to' provide a j ack possessing, these advantages, 1 which shallbe safe and l a strong, in which accurate centering and:

alinement off the workingparts is. readily;

obtained, and which is eas to repair; 7

In the accompanying rawings, forming part hereof: v a 1 Fig. 1 is avertical longitudinal" section t -through a jack embodyingtheainvention';;.

Fig. 2' is a section taken on the11ine:2 22- of Fig. 1;

Fi 3 is a section taken on -the line13 -'3 V ofF1g.2-;iand

of Fig. 3. r

The jack has a base' 2 from which rises a hollow cylindrical standard 3:These parts} an expensive casting as heretofore, 1 001151317 of:

instead 1 of being made in asingle'hea two pieces. The base is a castingformed with an upstandingcollar 4, which is braced to the outwardlyprojecting; ortion o'f theY base by ribs 5. Thestandar consists of atsectionof commercial tube which-isstepped into the collar 4" and restsatits lower endon theportion of the base inside the collar. A

transverse pin. G passing through the collar and the lower end of thestandard connects these arts firmly together. This. construe-V tionothe'base and standard affords a high. degreeof' strength while greatlyreducing, the weight and minimizing, the' amount of" machine workrequired. This portioniof the jack is'far lighter and. much less costlythan the usualf plan of a base. and'standard in one piece. A nut Fig. 4is asection taken on .the-line'iH projections on the 'shaft",-and'ispressed'into" V :spur gearby a spring 29. 7 is fixed-in the upperendofthe standard and is engaged by a steep pitchor run-down screw 8. A bevelgear il is secured 'infone side immediately belowthe head, the

lower edgeiof this opening bein remote from the lower end of the'-shellb bonnet 163 is applied over this opening; a'nd is securedto thesidefaceofthe shell by screws 17 a passing through basal flanges 18*onthe bonnet In the outer end of "the 1 bonnetthere is a bearing '19 for"an operating shaft 20, this shaft projecting outside the bonnet and being formed to receive the usual ratchet wheel and socketed ratchet case,which ithas not. been thought necessary 'toyillustrate since- 752. theyare well know'n. V t

A circular plate 21 is held in a-rebate 22" inthe' inner endbfthebonnet, between the shoulderof' the rebate and the outer'face of] theshell, and in the center of this plate there is a bearing 23. for theinner portion of the operatingshaft'. This bearing. is reliably.centered and alined with the bearing 19 by virtue ofthecircular' platefitting in the cir cular rebate: A bevel gear 24formed on ergo secured'to' thei'nner .endof the shaft at the side of theplate21whichfacesthein te'rior of the" 'shell,':mesheswith the bevel gear9.

At the other side of said plate, a spur gear 25' is mounted loosely onor; around the operatingjshaftf Thi'sfgear' has ratchet teeth 26 on itsouter face to engage ratchet teeth'on a clutch. co'llarf27, whichlikethe gearis 'slidablelengthwise ofthe'operatinq shaft'but-i heldthereto in respect to rotation y feather engagement with the"ratchetteethon the The-ratchet: teeth are so-formed that when thekshaft20 is turned-"inzthe-"direction torol tate the screw 8 to raise theshell 13,theratchet*- 10 0" teeth on the clutch collar ride idly overthe cooperating teeth on the stationary gear, the clutch collar movingback and forth on the shaft under the pressure of the spring. When thelifting effort ceases, the perpendicular faces of the teeth bear againsteach other, so that the shell is held against dropping, the

gear 25 being held against rotationin the' lowering direction by meanswhich will be described. Likewise, when the shell 13 is lowered, theshaft 20rotates the gear to operate the centrifugal brake or governorhereinafter described.

The bonnet 16 has a downward extension forming a supplementary gearchamber below the main chamber 28. i This extension is in onepiece withthe bonnet and provides integral spaced walls 31 and 32, in internalbosses of which the ends of a'fixed shaft 33 are supported, this shaftbeing parallel withthe rotary operating shaft 20.

Rotatable on thissha-ft 33 are a spur pinion 34 and a. worm wheel 35,which are suitably united together. -.-T he pinion 34 meshes with thegear 25, and the worm wheel meshes with aworm 36, the pitch of this wormgearing being. such that the worm wheel can drive the worm.

The worm is formed on a shaft 37 which extends horizontally in thelowest portion of the supplementary chamberin a plane at right an les tothe plane of the shafts 20 and 33. %)ne end of the shaft 37 is journaled in a bearing 38 in an integral end wall 39 of .the downwardextension 30 of the bonnet, and

a thrust bearing 40 is interposed at this end of the shaft.

Theother end of said extension is enlarged to form a chamber 41,thischamber having a mouth which is provided with an internal,cylindrical,machined surface 42. The mouth is closed by a cap 43 havingan inwardly projecting cylindrical flange 44 machined on the outside tofit themachined surface 42 of the bonnet, and machined on the inside tocooperate with the governor,as will presently appear. The capis held inplace by screws 45 and has'a'central boss 46 which affords a bearing forthe other end of the worm shaft 37, this bearing being accuratelyalined-with the bearing 38 by reason of the circular flange of the capfitting in the circular opening.

The portion of the shaft 37 within the enlarged chamber 41 is formedpolygonally to receive a governor disc 47. Carried by this 3 disc andslidable on its outer face are two the disc. 7

Recesses 53 are formed in the outer faces of the segments, near theirends, and studs 54 are set into the segments at the backs of theserecesses, the projecting heads of the studs lying within the recesses.The opposite ends of two. tension springs 55 are connected to the headsof these studs and normally draw the segments toward each other and awayfrom the encircling wall of the flange 44.

When the shell 13 and the load resting there- 'on are permitted todescend, the governor is rotated at considerable speed by the screw andgearing and clutch which have been described, and the segments are urgedoutward into braking contact with the encircling stationary surface, soas to retard the speed of lowering to a safe, uniform rate.

This form of governor is inexpensive to make and decidedly compact, inwhich respect it is an improvement over governors having tiltingsegments such as disclosed in my prior Patent 1,579,788 of April 6,1926, for example, and I find it to be perfectly sensitive and reliable.

In the cap 43 with its circular flange 44 fitting a circular opening andserving to center accuratelythe fixed and rotary parts of the governoras well as the. bearing for the worm and governor. shaft, the presentjack incorporates a feature covered by my patent aforesaid' Theenlargement 56 which provides the chamber 41 for the downward extension57, the lower end of which is formed with a vertical, inter! nallyscrew-threaded opening, which is engaged by a hollow screw 58. Thisscrew is formed with an external thumb piece 59, which lies in aprotected location beneath this extensionbf the bonnet.

A shaft 60 is pinned at 61 to the outer end of the screw 58, andprojects for a distance beyond the inner end of the screw. The inner endof this shaft has a head 62 which retains a manually operated brakesegment 63, theshaft being'swiveled in this segment. By means of thethumb piece 59 the brake segment 63 can be set against the periphery ofthe disc 47in accordance with my Patent 1,579,788 aforesaid, inorder tokeep the load from descending, or can be freed from the disc in order toallow the load to lower at a safe rate determined by the centrifugalgovernor brake.

It, will be perceived that the construction of the present jack is suchthat all the mechanism, other than the non-rotary nut 7, the

lifting screw 8 and the bevel gear 9 on the upper end of this screw. arehoused in the separate bonnet or casing unit 16, and that theconstruction of this bonnet and the man ner in which the partsare'mounted therein are such as to simplify machining, assembling andrepair, to facilitate the alining and cengovernor. has a.

tering of the working parts and to secure great rigidity withcomparative lightness.

The location of the mechanism well up at the top of the jack permits theprovision of the toe lift 14 at the lower end of the shell and stillleaves a smooth exterior of sufiicient length so that the jack can beconveniently carried on a mans shoulder.

I claim:

In a self-lowering screw jack, the combi-' nation with a shell having anopening in one side and the lifting screw having a bevel gear of aseparate bonnet applied to the side 0 the shell over said opening, saidbonnet having an integral pocket extension adjacent the shell, whichextension has inner and outer side walls, an end wall and an enlargementopposite said end wall, a cap closing said enlargement, an operatingshaft extending through and carried by said bonnet, the outer end ofsaid operating shaft being formed to receive manual operating means andits inner end having a bevel gear meshing the bevel gear on the screw, acentrifugal brake in said enlargement, and gearing, including anautomatic clutch, between said operating shaft and said brake, saidgearing being supported wholly on said operating shaft and by the twoside walls and ,the'end wall and cap of said pocket extension of thebonnet.

FRANK H. SCHW ERIN.

